People who booked tickets for a leading green festival cancelled in July are growing worried they will not be refunded, even though some handed over their cash almost a year ago, Guardian Money can reveal.

Up to 20,000 people were expected at this year's Big Green Gathering, a five-day festival in the Mendip Hills in Somerset, described as "a celebration of our natural world and our place within it", which was set to kick off on 29 July. But only days before the gates were due to open, the event was cancelled.

The directors claim they had no option but to voluntarily surrender the event licence after being "stitched up" by the police and council officials.

But whatever the reason, some of those who shelled out for tickets are unhappy that they are still waiting for their money.

It appears that those who bought via leading ticket agencies, from local shops or from tourist information bureaus, will get – or have received – a full refund, but people who booked directly with the organisation, either via its website or by sending a cheque to its office, are in a different position.

Last December, Liz Smith bought an "earlybird" ticket costing £115 directly from the Big Green Gathering office. "We'd been before to this festival and decided to go again this year," she says. Smith paid by cheque and says she received a receipt confirming tickets would be sent out in April, which did not happen.

Following the cancellation, information about refunds was put on the festival website. But, on downloading the refund form, Smith says she was irritated by the "flippant" and "patronising" tone.

The form certainly seems designed to encourage people to forgo most or all of their money. There are three options that allow ticket buyers to say they don't need a refund.

For example, they can tick a box to say they are happy to accept a free ticket to 2010's Big Green Gathering and, as long as they receive this, no longer require their money back. A fourth option allows people to donate some of the ticket price to the "cause".

After that comes a section headed "Full refund required", where people have to tick a box stating: "I'm sorry but I really need to ask for that refund in full. I recognise that it may take some while to process, and that it's touch and go how much I'll get or quite when I'll get it but hey, it's not my fault that the festival didn't go ahead."

It was this part of the form that particularly annoyed Smith, who lives in west Dorset. She was not prepared to sign it, because it meant she was effectively accepting she may not get her money back, and she did not want another ticket. She says she has sent a number of emails requesting a refund but received automated replies directing her to the website.

"There are lots of us in the same boat, I'm sure. I'm annoyed that not only could I not enjoy the festival, but that my £115 has been in the hands of the directors for 10 months, with what appears to be little hope of a refund, even though the website informs ticket holders that it is their legal entitlement. I would have thought insurance to cover such an occurrence would be in place."

The normal standard adult price was £125. While the form talks about the possibility of putting their money towards the cause, the Glastonbury-based Big Green Gathering Co Ltd is not a charity; it describes itself on the website as a "not-for-profit democratic company".

And the suggestion people could accept a free ticket to next year's event should perhaps come with a warning, because it is far from certain there will be one. Monbiot wrote in August that the Big Green Gathering "will now go bankrupt. It's unlikely ever to happen again".

The website gives more details on refunds. It states that "We are still assessing the very damaging financial consequences of this enforced cancellation, and this will inevitably take some time, so we have to ask for your patience … Please do see if you can reuse your ticket at another event, as this reduces our overall debts and is one of the best ways to help keep the BGG in business."

It goes on: "Unfortunately, if you booked directly with us, either through our website or by sending a cheque to our office, the situation is a lot more complicated.

"The truth is that if everyone were to claim a refund from the BGG, there would not be enough money to go around, as we had spent nearly £300,000 on infrastructure and event costs … We know this is a big ask, but we are asking everyone who can to hold off requesting a refund for their tickets. If the BGG is to survive, we desperately need your support and co-operation in the short term, and expect to pay everyone in full with another event in 2010.

"Without that support, we could end up in the hands of the receivers, with our creditors (including ticket holders) ending up with only a small percentage of what they are owed."

Money tried to phone the number on the website but was met with a recorded message, saying: "Sorry, this mailbox is full, it can't accept any more messages." We emailed the organisation but have not received a reply.

Normally, if a gig or festival is cancelled, refunds should not be a problem, though whether you get all your money back will depend on who you booked with.

Ticketmaster will refund the face value of the ticket, plus the booking fee. By contrast, See Tickets will normally refund only the face value.